Question

Which of the following would cause the greatest decrease in GFR in a person with otherwise normal kidneys?a. Decrease in renal arterial pressure from 100 to 80 mmHg in a normal kidneyb. 50% increase in glomerular capillary filtration coefficientc. 50% increase in proximal tubular sodium reabsorptiond. 50% decrease in afferent arteriolar resistancee. 50% decrease in efferent arteriolar resistancef. 5 mmHg decrease in Bowman's capsule pressure

Answer 1

Answer: 50% decrease in afferent arteriolar resistance

Explanation: This is because the afferent arteriole is responsible for supplying blood to the glomerulus, where filtration occurs. If the resistance of the afferent arteriole decreases, more blood will flow into the glomerulus, increasing the hydrostatic pressure and causing an increase in GFR. Conversely, if the resistance of the afferent arteriole increases, less blood will flow into the glomerulus, decreasing the hydrostatic pressure and causing a decrease in GFR.

Answer 2

A 50% decrease in efferent arteriolar resistance would cause the greatest decrease in GFR in a person with otherwise normal kidneys.

Step-by-step explanation:

The greatest decrease in GFR in a person with otherwise normal kidneys would be caused by a 50% decrease in efferent arteriolar resistance (option e). When the resistance in the efferent arteriole decreases, more blood will exit the glomerulus, resulting in a decrease in filtration and a decrease in GFR. This is because the efferent arteriole plays a crucial role in regulating the pressure within the glomerulus.

The other options would not cause as significant of a decrease in GFR. For example, a decrease in renal arterial pressure (option a) would affect the overall blood flow to the kidneys, but it would not directly impact GFR. Similarly, changes in glomerular capillary filtration coefficient (option b) or proximal tubular sodium reabsorption (option c) would have a lesser effect on GFR.

Therefore, the 50% decrease in efferent arteriolar resistance would cause the greatest decrease in GFR in a person with otherwise normal kidneys.